THE SECRET SPIES IN THE SKY - Imagery, Data Analysis, and Discussions relating to Military Space

SatTrackCam Leiden (Cospar 4353) is a satellite tracking station located at Leiden, the Netherlands. The tracking focus is on classified objects - i.e. "spy satellites". With a camera, accurate positional measurements on satellites of interest are obtained in order to determine their orbits. Orbital behaviour is analysed.

Thursday, 14 January 2010

Weather conditions obviously have a major impact on the activities at SatTrackCam Leiden. Last two weeks for example have seen a lot of snow, and consequently clouded skies.

I have had an outdoor thermometer for some time, but manually logging a strict temperature record proved too cumbersome to uphold. However, as of this week I have a fully computerized weather station here at SatTrackCam Leiden which logs information on temperature, air pressure, wind, air moisture and rainfall on a 15-minute basis. The station sends the data wireless to a receiver in my home, where it is logged in the receiver memory. The receiver can be attached to the pc by USB.

Hence, I now have the opportunity to record basic weather data in detail for my location.

Below pictures show the basic outdoor rig, and a picture of SatTrackCam Leiden in the snow on january 10th.

Saturday, 9 January 2010

Yesterday evening (Jan 8) started clear. I captured GOCE (09-013A) flaring again, and then observed Lacrosse 3 (97-064A). I also tried the HEO objects USA 179 and 198 but due to a mistake in software parameters I keyed in, I photographed the wrong sky locations...

Next the sky got clouded again, the forerunners of snow.

The GOCE flare behaviour is by now getting familiar (if still in aspects unexplained: see the previous post). This time, the flare occurred at 17:02:55.1 UTC (Jan 8). This corresponds to an angle of 93.4 degrees and a tilt of 25.8 degrees.

Below is the picture and the resulting brightness diagram.

click images to enlarge

I also photographed a GOCE flare on 5 January, under appaling sky conditions. Start and end of the trail were not visible (hence, I cannot produce a brightnes sprofile for that flare) and in fact the flare even shos up only marginally (see image below). By measuring the brightest point of the flare and comparing to the GOCE orbit, it resulted in a flare time though: 17:15:48.1 UTC (Jan 5). This corresponds to an angle of 93.2 degrees and a tilt of 37.8 degrees.

Monday, 4 January 2010

With four timed brightness profiles now available for GOCE flares, I created a comparison chart.

In this diagram, each profile has been shifted in Y value to keep them clearly separated. The delta values refer to the offset of the observed flare path tilt and the theoretical panel tilt (either 67.5 or 22.5 degree, depending on which panel caused the flare). This is a measure of distance to the theoretical central flare path.

As can be seen, there appears to be no clear correlation between delta/distance and the quality of the flare peak.

The profile for November 26th 2009 is less reliable as it suffered from thin cloud interference.

click diagram to enlarge

The flares are (perhaps - see below) caused by the solar-panel covered sun-facing side of the space probe:

With regard to the identification of the panels: below is a schematic cross-section of the GOCE probe. Two solar panels on the solar-facing side of the eight-plane shaped probe are responsible for the flares: one inclined at 22.5 degree and one at 67.5 degree.

click image to enlarge

This creates the geometric situation below (with the green trails being the theoretical central flare paths for the two panels indicated):

click image to enlarge

There is a baffling aspect to these flares and this model though. Flares from flat panels should be highly specular ("narrow") in both directions: angle and tilt. In essence: with regard to the probe's major axis (angle) and minor axis (tilt).

But they are not!

They are highly specular in angle ( = with regard to the probe's long axis) as evidenced by the short duration of the flares (FWHM ~0.5s). But not in tilt.

This is not what you expect from a satellite with an angular surface such as GOCE: it is what you expect from a tubular object (which GOCE isn't). This is a bit baffling. It could mean it aren't actually the solar panels which are causing the flaring behaviour, but some other part of the GOCE body. Problem is, there is no clear candidate for it...

Yesterday evening started very clear, but ended cloudy. Nevertheless I was able to bag several objects: the Lacrosses 2 & 3, the NOSS 3-4 Centaur rocket, GOCE flaring, and the HEO objects USA 179 and USA 184.

GOCE (the European Gravity field and steady state Ocean Circulation Explorer) made a zenith pass, zipping close to M31 at mag. +4 to +5 and then flaring briefly to mag. +2 at 17:24:23.15 UTC. It was nice to watch. GOCE is in a very low orbit and moves very fast: the flare almost looks like a meteor to the eye.

The flare was caused by the 67.5 degree panel and the time yields a flare angle of 93.6 degree and tilt of 51.9 degree. The 93 degree angle is consistent for all GOCE flares I so far observed (theoretically, that angle should be 90 degrees, i.e. at the moment of culmination when the sun-observer-satellite flight direction makes a square angle). The miss distance to the theoretical central flare path (quite large in this instance: some 175 km!) doesn't really seem to matter with regard to the flare brightness: they always come out at +2 to +3 (even when, as in this case, the tilt is off from 67.5 degree by over 15 degrees).

Below is the image, the derived brightness profile (edit - please note that the time stated in the upper left corner of the diagram is wrong: I inadvertently mentioned the end of the exposure here instead of the flare peak time), and the observing geometry. Note how the flare peak is slightly asymmetrical, the descending branch is slightly steeper.

Saturday, 2 January 2010

2010 started off well with a very clear evening of January 1st. I observed GOCE (09-013A), the Lacrosses 2 & 3 (91-017A & 97-064A), the tumbling NOSS 3-4 Centaur rocket (07-027B), and the HEO objects USA 179, 184 and 200.

I was treated to two small flares: one by GOCE (09-013A) and one by Lacrosse 2 (91-017A).

The GOCE flare was a mild one to about +3, at 17:32:58.0 UTC. It was caused by the 67.5 degree panel. The time of the flare (accurate to 0.1s) yields an angle of 93.2 and tilt of 66.3 with a nominal mis distance to the theoretical flare path (angle 90 degrees, tilt 67.5 degrees) of 19.4 km at the time of observation (and closest approach to 17.1 km 1.2 seconds earlier at 17:32:56.8 UTC).

So far, all the GOCE mild flares I observed were with an angle ~93 degrees. The distance to the nominal flare path of this one was much less than for the three flares previously observed by me, but that doesn't seem to have much influence on the observed flare brightness: they were all around +3 magnitude.

Below are the picture, the derived brightness profile, and a depiction of the flare path geometry based on Simone Corbellini's Visual Sat-Flare Tracker 3D software.

click images to enlarge

Unexpectedly, I also captured a brief (<0.5s) flare/glint by Lacrosse 2 (91-017A) at 17:56:58.4 UTC. Below is the image and the resulting brightness profile:

About the Author

Dutch, 47, PhD, stone age archaeologist, meteoriticist, satellite tracker, meteor observer, asteroid discoverer. Consultant in a Space Situational Awareness project with the Space Security Center of the Royal Dutch Air Force and Leiden Observatory. As an invited expert I advised members of Dutch Parliament about military satellite systems and their locations during a 2016 foreign affairs committee hearing about the MH17 disaster.
Asteroid (183294) Langbroek was named after me. In 2012, I received the Dr. J. van der Bilt Prize of the Royal Dutch Astronomy Association (KNVWS) for my work on meteors, asteroids and satellites.
Opinions expressed on this blog are entirely my own.
You can find me on Twitter via @Marco_Langbroek

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Excerpt from United Nations resolution 2222 (XXI)

Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies

In order to promote international co-operation in the peaceful exploration and use of outer space, States Parties to the Treaty conducting activities in outer space, including the moon and other celestial bodies, agree to inform the Secretary-General of the United Nations as well as the public and the international scientific community, to the greatest extent feasible and practicable, of the nature, conduct, locations and results of such activities. On receiving the said information, the Secretary-General of the United Nations should be prepared to disseminate it immediately and effectively.